Holland, you forgot one of the major advantages of dry sumps! :) Having a dry sump system allows for the chassis designer to lower the engine placement within the car quite a bit, lowering the overall CG significantly.
-- Akira Sasaki '90 Jetta GLi <- white, with small bumpers > From: "Holland J. Phillips" <[email protected]> > Date: Fri, 25 Feb 2000 08:21:53 -0800 > To: jimvish <[email protected]>, [email protected] > Subject: Re: Dry Sump/Pressurized Oil System > >> what is the difference between dry sump and a plain old pressurized >> system. Just the fact that there isn't an oil pan on a dry sump system, >> right? > > I assume by "plain old pressurized system" you mean the stock oiling system. > > Now, a true dry sump system consists of a large oil tank (usually about 14 > quarts - 3.5 gallons for a 4 cylinder application) which is mounted in the > rear of the car (hatch or trunk), feed and return lines to the engine > compartment, a belt driven high pressure pump, a sort of convex plate that > replaces the oil pan that has a fitting at it's lowest point for the oil > return to the tank, and various high pressure feed lines from the pump to > the engine. There may be a low pressure transfer pump in/near the tank, and > there may or may not be an oil cooler somewhere along the line - probably > not necessary with that large of volume of oil and length of supply/return > lines. > The advantages are multi fold. Putting the holding tank in the rear > (usually) helps weight distribution, the fact that the tanks are usually > fairly tall and narrow, and that the feed line is located at the bottom of > the tank, means that no amount of cornering/acceleration/braking force can > cause the oil to "slosh" away from the supply line, therefore allowing for > constant positive oil pressure. The large volume of oil affords very stable > oil temps, as well as a much higher dilution factor in regards to > contaminants in the oil. The fact that there is virtually no oil sitting > below that crankshaft means that there is less HP loss from the crank having > to "slice" through the oil in the oil pan. > The down side is cost (a whole dry sump system is MAJOR $$), and loss of > trunk/hatch space, which isn't an issue in a race car. The more cost > effective way to deal with this is to get/fabricate a well baffled oil pan, > and, possibly, get a device called an "Accusump", which is a small (1 or 2 > quart) cylinder, similar in appearance to a fire extinguisher, that mounts > vertically in the engine compartment, and is plumbed into the oiling system > so that the supply to the pump comes from the bottom of the cylinder, and > the return is attached to the top. This setup retains the oil pan and stock > pump, but works like a dry sump system in regards to having a constant oil > supply which is not affected by cornering/acceleration/braking, without the > large tank and belt driven pump. > The Accusump system can also be used as a pre-oiler to provide positive oil > pressure prior to starting the engine. > > I think that about covers it, but feel free to ask any questions... > > --Holland > Forced Failure Racing > Don't Ask MotorSports > [email protected] > a2_16V List Owner > [email protected] > San Jose, California > > > _____________ > List Sponsor: http://www.netsville.com > To remove yourself from this list, send mail to [email protected] with > 'unsubscribe a2_16v' in the body of your message > See us on the web at http://www.a2-16v.com > Visit the 16V Homepage at http://www.gti16v.org _____________ List Sponsor: http://www.netsville.com To remove yourself from this list, send mail to [email protected] with 'unsubscribe a2_16v' in the body of your message See us on the web at http://www.a2-16v.com Visit the 16V Homepage at http://www.gti16v.org
